The ways to reduce laser cutting burn marks (anti-reflection)

The ways to reduce laser cutting burn marks (anti-reflection)

Preface：

During the laser cutting process on a honeycomb platform, the laser beam strikes the honeycomb holes and is reflected onto the material surface. The reflected laser can leave burn marks on both sides of the cut seam, affecting the product's appearance.


                                                            Principle of Burn Mark Formation

The image below shows the burn marks on the back side of the material, as well as on both sides of the cut seam.

Burn marks affect the product's appearance
To effectively address burn marks, simply lowering the power may not be sufficient. To eliminate them, consider trying the following 6 tips.
Prop up item
The laser energy reflected by the honeycomb holes is relatively low. By raising the material to be cut a few millimeters with support, the material will not be affected by the laser reflected from the honeycomb holes. This method is suitable for sheet materials.

1.Knife Blade Platform


The knife blade platform is a type of platform composed of strips with upward-pointing sharp edges. Thunderlaser's laser cutting machines and laser engraving machines are equipped with a knife blade platform beneath their honeycomb platforms. The knife blade on the knife blade platform is spaced far apart, and the contact area between the knife blade and the material is small. Using a knife blade platform helps reduce the reflection of the laser beam during the cutting process, thereby minimizing the burn marks caused by cutting.  


    
                                                            Machine's knife blade platform

If small-sized materials need to be processed but the gap between the strips on the knife blade platform is too wide, or if it’s inconvenient to remove the honeycomb platform, the knife blade can be directly placed on the honeycomb platform without being fixed. The knife blades should be placed with the sharp edge facing up and can be arranged either vertically or horizontally. This effectively supports the material to be cut, helping to prevent the material from being affected by the laser reflection.


                                     Place the knife blade on the honeycomb table

                                                                  Place the blade horizontally

2. Clamps

If using a knife blade platform is considered inconvenient or unsafe, a set of custom-made clamps can be used. Clamps are a less commonly used auxiliary tool in laser processing, but they are aesthetically pleasing, easy to use, and suitable for fixing materials, flattening materials, and reducing reflection marks, among other purposes. The clamps are made from 3mm basswood, magnets, acrylic, and hinges through laser cutting.

Clamps are suitable for hard materials. To use, simply clamp the material with the clamp and place it on the honeycomb platform. Alternatively, place the clamp on the honeycomb platform, adjust its position, open it, place the material inside, and close the clamp to secure the material. The clamp creates a gap between the material and the honeycomb platform, preventing direct contact and reducing the laser beam energy that reaches the material, thus minimizing burn marks.





3. Double-Layer Pin

Among various types of pins, the F-shaped (double-layer anti-collision pin) is suitable for reducing reflection burn marks. The double-layer pin clamps the material in place, creating a gap between the material and the honeycomb platform, rather than allowing them to be in direct contact. This helps reduce the laser beam energy reaching the material, thereby minimizing burn marks.

When using the pin, insert the material into the groove of the F-shaped pin, grip the pin handle, and insert the pin rod into a honeycomb hole near the edge of the material. Twist and adjust to secure it. If additional support is needed, more F-shaped pins can be added. The F-shaped pin is designed in such a way that it will not collide with the laser head or automatic focus head during use.



4.Magnets

Magnets are inexpensive, easy to purchase, and one of the most commonly used auxiliary tools in laser processing. We can place several magnets of the same thickness on the honeycomb platform and position the material on top of them. If the material is severely warped, we can place additional magnets or magnet pieces on the corresponding area above the material. The magnetic force between the two sets of magnets will help flatten the material.

Precautions:

  1. If thicker magnets are used to flatten the material, check the height before processing to avoid collision with the laser head or automatic focus head. If a collision is likely, adjust the magnet position to ensure that the magnets do not come into contact with the laser head or automatic focus head during processing.
  2. Place the material first, then adjust the laser head for focusing.
  3. Be cautious to avoid pinching your fingers between magnets as they attract each other.
 



Non-Reflective Padding

Placing a non-reflective, stain-free padding material under the material being cut can help prevent burn marks from occurring during the laser cutting process. This method is suitable for softer materials like fabrics or paper.

5.Acrylic Padding

For materials that are lightweight and thin, such as paper or fabric, where using support methods may not be suitable, we can place an acrylic sheet larger than the cutting size beneath the material to be cut. Acrylic does not reflect the laser and will not produce noticeable stains during the laser cutting process, thus preventing contamination of the material being cut. Acrylic is an ideal padding material. Place the material to be processed on the acrylic sheet, flatten or smooth it out, and proceed with the cutting. This will prevent burn marks on the back side of the material.

Precautions: The surface of the acrylic sheet used as padding may leave trace-like marks, similar to engraving lines. This is caused by excessive laser power, which penetrates the material being processed.

Protective Layer

By adding a protective layer to the back of the material to be cut, burn marks will form on the protective layer instead of the material itself. After cutting, the protective layer can be peeled off, leaving the material clean. This method is suitable for sheet materials.

6. Backside Protective Paper

For rigid materials, there is no need to place an acrylic sheet beneath the material. Instead, we can directly apply a layer of masking tape to the back of the material. During cutting, the burn marks caused by the laser beam reflection will be left on the masking tape layer, not penetrating through to the material. After processing, simply peel off the masking tape to reveal a clean material surface. If the material to be cut already has a protective paper layer, such as acrylic, just leave the protective paper on the bottom of the sheet and remove it after processing.

Precautions:

  1. When applying the masking tape, make sure it is smooth and free of bubbles or wrinkles. Otherwise, the material may become uneven, affecting the processing result.
  2. If burn marks penetrate through the masking tape and remain on the material after applying a single layer, consider applying one or more additional layers of masking tape for better protection.

The processing files for clamps and Double-Layer Pin can be downloaded from the attachment.  


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End.

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